so my son runs a box stock class in south east wisconsin, last year i bought a brand new Lo206 right from a briggs dealer, we ran it all year in Jr 1 box stock (purple slide) basically all i had to do was adjust the float a bit and everything ran great, the kid ended up winning 4 features and the championship with it, so the season ends i take the lo206 off put it on the shelf and throw the clone stuff on to get ready for indoor season, anyways fast forward to now its spring and we are back to running locally hear so i take lo206 back off the shelf put it on the kart cleaned the carb and we actually moved him up to Jr 2 so now thats Gold or Yellow slide so obviously i switched the slides, which i figured was no big deal or atleast it should'ent be, we went to practice last week and its backfiring when he gets out of the gas, now i have read just about every thread on here and some people say its no big deal if its not hurting the performance and its only happening when he gets out of the gas entering a corner or whatever it may be, but here's the deal last year this engine never backfired not one time at all, ran great no issues, all i did was switch the slide that's it now all in the sudden i got backfire, it aggervates the **** out of me honestly, i spent hours and hours trying to figure out what im missing here, last night i pulled the carb completly apart cleaned the jets, reset the float hight which is .880 and 1.050, i ran it at .880 all last year seemed to run better at that height which i know is a little lean, but to this point have'nt had an issue, i reset the valve lash it was at 0 i adjusted to .002 on both intake and exhaust, if any anyone has any ideas as in like here try these setting on the carb and valve lash and see what happens or an idea to get rid of the back fire please im all ears or in this case eyes lol, i very much appreciate any input from everyone.... huge fan of BOBS been on here for years reading peoples opinions this sight really is like gold for people like myslelf who know just anough to get myself in trouble!!! also our local track is Beaver Dam Wisconsin its a 1/5th mile with slight bank we run a 2018 triton Jr on burris
lo206 yellow slide backfiring from exhaust when decelerating PLEASE HELP!!!!
- Thread starter Sivia91
- Start date
also last night i ran it on the stand and it seems not to back fire when controlling the throttle with my hand and i let off the throttle very slowly, like almost if you were to just ease out of the gas it may not backfire, but trying to get a 11 year old to "EASE" out of the gas is like gettingf him to eat green beans it just aint gonna happen lol
One Fast Kat
Member
One Fast Kat
Member
Flattop 1 is correct or you have a hole in the pipe.
Have you tried raising the needle, or raising the float.
Fuel filter is clean, pump in good condition, vent hose not pinched?
Just some thoughts.
I'm leaning also towards exhaust, either gasket, or pipe cracked.
Sometimes letting a little air into the exhaust can help performance on restricted engines.
Fuel filter is clean, pump in good condition, vent hose not pinched?
Just some thoughts.
I'm leaning also towards exhaust, either gasket, or pipe cracked.
Sometimes letting a little air into the exhaust can help performance on restricted engines.
Thank you all for the replies, honestly I didn’t even think to check that seems how that gasket was literally just replaced last week, we had these issues during our first practice night and I ended up sending the motor down to our engine builder, which in turn he replaced the gasket... but anyways looks to me like that is the issue for sure... looks to me like the flange is bent... that’s the second gasket I took off that looked like that almost identical so obviously now we know we have an issue with the pipe itself at least I’m hoping and it’s not the head
Typically the further out you have the air bleed screw and the leaner the needle clip the more backfiring you’ll have. Put it on clip 4 second from the bottom and it will probably go away completely if that’s all you care about. It has nothing to do with valve lash and your header isn’t leaking enough to cause it either. You should use high temp silicone even when using the copper gasket.
CarlsonMotorsports
Site Supporter
I don't see any sealant on that gasket. The metal gaskets need sealant to do the sealing. The gasket itself simply protects the port face from damage in case the pipe were to come loose or get crashed. that is also one of the Target import gaskets that's not all copper like the RLV gasket. The metal is much more brittle (harder) and doesn't compress as well to seal. Not a problem as long as you are using sealant, however.
If it were hesitating or popping/coughing during acceleration, then I'd agree with Gary on it being too lean on the needle. Being that you haven't mentioned that, I am guessing you are simply too rich on mixture and you are getting raw fuel igniting in the hot pipe during deceleration (off throttle.) This is typical on a 4 stroke (including the 206.)
Is the gasket leaking enough to cause the super-heating and ignition? Possibly, but not likely. I'd still seal that gasket with hi temp sealant.
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"J'-remy
Member
A back fire is unburnt fuel exiting the exhaust pipe. it ignites in the 1200 degree gasses in the pipe but without oxygen it cant burn. when it reaches the air (oxygen) it ignites and you get the POP. this is a sign of a rich situation not lean. however if you abruptly cut the fuel supply at full throttle backfiring is not untypical. do have a leaky exhaust gasket but if the fuel is burnt in the cylinder there is nothing to backfire.